1. Date of download: 11/15/2017
Copyright © ASME. All rights reserved.
From: System-Level Biomechanical Approach for the Evaluation of Term and Preterm Pregnancy Maintenance
J Biomech Eng. 2013;135(2): doi: /
Figure Legend:
Schematics showing geometric changes in the uterine and cervical anatomy. The mass and volume of the human uterus and cervix increase with gestational age. The uterus typically increases in length from 6.5 cm to 32 cm and from 60 g to 1000 g in mass. The cervix increases in overall size, but gets progressively shorter after 24 weeks, from 4–6 cm. As the cervix nears term, the internal os increases in diameter and first opens with progressive cervical shortening. The anatomy of the cervical canal is typically described in terms of its shape, beginning as a ‘T,’ opening to a ‘V,’ and finally progressing to a ‘U’ as labor nears [20].

2. Date of download: 11/15/2017
Copyright © ASME. All rights reserved.
From: System-Level Biomechanical Approach for the Evaluation of Term and Preterm Pregnancy Maintenance
J Biomech Eng. 2013;135(2): doi: /
Figure Legend:
Schematic of the forces that act on the uterus and cervix before (left) and during dilation (right) include myometrial contraction, gravitational force, and boundary conditions from round, broad, and uterosacral ligaments. Cross-sections of the cervix illustrate the changes in dilation, collagen fiber arrangement, and lateral boundary conditions from the ligaments.

3. Date of download: 11/15/2017
Copyright © ASME. All rights reserved.
From: System-Level Biomechanical Approach for the Evaluation of Term and Preterm Pregnancy Maintenance
J Biomech Eng. 2013;135(2): doi: /
Figure Legend:
Cervical remodeling in normal pregnancy starts with cervical softening very early in pregnancy. Later in pregnancy, the collagen disorganizes and collagen fibers disorganize [48].

4. Date of download: 11/15/2017
Copyright © ASME. All rights reserved.
From: System-Level Biomechanical Approach for the Evaluation of Term and Preterm Pregnancy Maintenance
J Biomech Eng. 2013;135(2): doi: /
Figure Legend:
Representative data from the literature showing the complex mechanical behavior of uterine tissue. (a) The nonlinear elastic behavior in the stress-elongation data and differences for pregnant versus non pregnant tissue [69]. Nonpregnant uterine tissue is stiffer than pregnant tissue for the entire range of stress and elongation shown. (b) Representative examples of anisotropic and viscoelastic behavior in uterine tissue. The complex modulus depends, to a great extent, on the collagen fiber orientation, loading frequency, and amount of precompression. In addition to the complex modulus being greater for loading parallel to fibers, it also increases with increasing loading frequency [71].

5. Date of download: 11/15/2017
Copyright © ASME. All rights reserved.
From: System-Level Biomechanical Approach for the Evaluation of Term and Preterm Pregnancy Maintenance
J Biomech Eng. 2013;135(2): doi: /
Figure Legend:
The 2D finite element models of the ‘T’ and ‘U’ geometries

6. Date of download: 11/15/2017
Copyright © ASME. All rights reserved.
From: System-Level Biomechanical Approach for the Evaluation of Term and Preterm Pregnancy Maintenance
J Biomech Eng. 2013;135(2): doi: /
Figure Legend:
Deformation (widening) of the seven springs representing the cervical canal. An increase in the pressure results in increased widening ((a) versus (b), (c) versus (d)), as does softening of the tissue ((a) versus (c), (b) versus (d)). The greatest deformation of ‘T’ cervices is located at the internal os, while the greatest deformation of ‘U’ cervices is shifted towards the external os.